With a conventional image processing apparatus that detects the direction of attention of a person, the face area of a person of interest is extracted from an image acquired by camera imaging, an eye area of a part corresponding to a human eye is detected from that area, and the line of sight direction is detected from that eye area by means of image processing.
However, with this kind of apparatus, only detection of the line of sight direction is performed, and it is not determined whether or not the person of interest is paying attention in that direction.
Therefore, the relationship between information acquired by an image processing apparatus and the intention of a person of interest in terms of whether or not that person of interest is paying attention in that direction is unknown, and ways of using the acquired information are limited.
In response to this problem, a direction-of-attention detection method has been proposed whereby, as a means of determining the attention level—that is, the degree of attention—of a person, a face direction is found at fixed discrete times, a temporal variation pattern and statistics are calculated, and the attention state of the person is estimated by comparing these with previously obtained standard reference data (see Patent Document 1, for example).
Also, an attention level determination method has been proposed whereby a person of interest is determined to be paying attention if an object of interest is moved and the line of sight moves in line with that movement (see Patent Document 2, for example).
There are also other attention level determination methods, such as dividing a document into a plurality of areas, setting an area attention level for each area, and taking the sum thereof as the document attention level.
With this method, if the line-of-sight dwell time is long, or there are a plurality of dwell times, the area attention level is increased, and if that area is not being looked at even though the object is being looked at, attenuation is performed gently in area attention (see Non-patent Document 1, for example).
Patent Document 1: Japanese Patent Application Laid-Open No. HEI 9-147119
Patent Document 2: Japanese Patent Application Laid-Open No. 2004-62393
Non-patent Document 1: Takehiko Ohno, Interactive Systems and Software, WISS 2000, pp. 137-146, 2000